Zhiwen Chen

Altered DNA polymerase iota expression in breast cancer cells leads to a reduction in DNA replication fidelity and a higher rate of mutagenesis.

The recently discovered human enzyme DNA polymerase ι (pol ι) has been shown to have an exceptionally high error rate on artificial DNA templates. Although there is a considerable body of in vitro evidence for a role for pol ι in DNA lesion bypass, there is no in vivo evidence to confirm this action. We report here that pol ι expression is elevated in breast cancer cells and correlates with a significant decrease in DNA replication fidelity. We also demonstrate that UV treatment of breast cancer cells additionally increases pol ι expression with a peak occurring between 30 min and 2 h after cellular insult. This implies that the change in pol ι expression is an early event after UV-mediated DNA damage. That pol ι may play a role in the higher mutation frequencies observed in breast cancer cells was suggested when a reduction in mutation frequency was found after pol ι was immunodepleted from nuclear extracts of the cells. Analysis of the UV-induced mutation spectra revealed that >90% were point mutations. The analysis also demonstrated a decreased C→T nucleotide transition and an increased C→A transversion rate. Overall, our data strongly suggest that pol ι may be involved in the generation of both increased spontaneous and translesion mutations during DNA replication in breast cancer cells, thereby contributing to the accumulation of genetic damage.

Detection of Nanobacteria Infection in Type III Prostatitis

OBJECTIVES To investigate the relationship between nanobacterial infection and type III prostatitis. The etiology of type III prostatitis remains unclear to date, although the recently discovered nanobacteria (NB) have been implicated in this disease. METHODS A total of 48 patients with chronic pelvic pain syndrome for whom conventional therapy had failed were selected and randomly divided into two groups, one receiving anti-NB treatment and the other receiving a placebo. The NB were isolated and cultured from expressed prostatic secretions and urine samples before and after treatment. The morphologic features were recorded and 16s rRNA gene expression was determined. The curative effect was evaluated by the NB-positive rate and symptomatic changes using the National Institutes of Health Chronic Prostatitis Symptom Index. RESULTS After anti-NB treatment, the NB-positive rates had decreased from 62.5% to 16.7% in the expressed prostatic secretions and from 12.5% to 0% in the urine samples after prostatic massage (P <0.001). In the patients receiving a placebo, the positive rates had no obvious change in either the expressed prostatic secretions or the urine samples after prostatic massage (P >0.05). The NB were coccoid or coccobacillary and clustered in a diameter of 100 to 500 nm. The BLAST result revealed that the 16s rRNA gene sequence from the NB in the patients with chronic pelvic pain syndrome was 97%, similar to that of the known NB with identity (97%). After anti-NB treatment, the Chronic Prostatitis Symptom Index scores decreased significantly. In contrast, no change in the Chronic Prostatitis Symptom Index scores was seen after placebo treatment. CONCLUSIONS The results of our study have shown that nanobacterial infection might be an important etiologic factor of type III prostatitis. Anti-NB treatment could be an effective therapy against refractory type III prostatitis.

Attenuated expression of xeroderma pigmentosum group C is associated with critical events in human bladder cancer carcinogenesis and progression.

Xeroderma pigmentosum group C (XPC) is an important DNA damage recognition protein that binds to damaged DNA at a very early stage during DNA repair. The XPC protein is also involved in DNA damage-induced cell cycle checkpoint regulation and apoptosis. XPC defects are associated with many types of solid tumors. The mechanism of the XPC protein in cancer progression, however, remains unclear. In this report, we showed the strong correlation between bladder cancer progression and attenuated XPC protein expression using tissues derived from patients with bladder cancer. The results obtained from our immunohistochemical studies further revealed a strong correlation of XPC deficiency, p53 mutation, and the degree of malignancy of bladder tumors. In addition, the results obtained from our studies have also shown that HT1197 bladder cancer cells, which carry a low-level XPC protein, exhibited a decreased DNA repair capability and were resistant to cisplatin treatment. When an XPC gene cDNA-expression vector was stably transfected into the HT1197 cells, however, the cisplatin treatment-induced apoptotic cell death was increased. Increased p53 and p73 responses following cisplatin treatment were also observed in HT1197 cells stably transfected with XPC cDNA. Taken together, these results suggest that XPC deficiency is an important contributing factor in bladder tumor progression and bladder cancer cell drug resistance.

Suppression of CX43 expression by miR-20a in the progression of human prostate cancer.

The aberrant expression of microRNAs (miRNAs) has been found in various types of cancer. The present study found miR-20a to be significantly upregulated in prostate cancer compared with normal prostate tissues. The proliferation and colony formation assays revealed that the downregulation of miR-20a by miR-20a inhibitor suppresses the proliferation of MDA-PCa-2b cells in vitro and also inhibits tumor growth in vivo. Furthermore, a gap junction protein, α 1 (CX43), was identified as a direct target gene of miR-20a. The upregulation of CX43 was detected in MDA-PCa-2b cells after treatment with miR-20a inhibitor both in vitro and in vivo. In conclusion, the findings show that miR-20a significantly contributes to the progression of prostate cancer by targeting CX43.

Interaction between Polymorphisms of DNA Repair Genes Significantly Modulated Bladder Cancer Risk

DNA repair is a primary defense mechanism against damage caused by exogenous and endogenous sources. We examined the associations between bladder cancer and 7 polymorphisms from 5 genes involved in the maintenance of genetic stability (MMR: MLH1-93G>A; BER: XRCC1--77T>C and Arg399Gln; NER:XPC Lys939Gln and PAT +/-; DSBR:ATM G5557A and XRCC7 G6721T) in 302 incident bladder cancer cases and 311 hospital controls. Genotyping was done using a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) technique. The homozygous variant of XRCC7 G6721T (Odds Ratio [OR]: 2.36; 95% Confidence Interval [CI]: 1.13-4.92) was associated with increased bladder cancer risk. In an analysis of combined genotypes, the combination of XRCC1Arg399Gln (Gln allele) with XRCC1-77 T/T led to an increase in risk (OR: 1.61; 95% CI: 1.10-2.36). Moreover, when the XPCLys939Gln (Gln allele) (nucleotide excision repair [NER]) was present together with XRCC7 (T allele) (double strand break repair [DSBR]), the bladder cancer risk dramatically increased (OR: 4.42; 95% CI: 1.23-15.87). Our results suggest that there are multigenic variations in the DNA repair pathway involved in bladder cancer susceptibility, despite the existence of ethnic group differences.

XPC Epigenetic Silence Coupled With p53 Alteration Has a Significant Impact on Bladder Cancer Outcome

PURPOSE Varied XPC genetics are related to bladder cancer susceptibility. We determined whether decreased XPC expression influences bladder cancer malignancy and clinical outcome. MATERIALS AND METHODS Changes in XPC and p53 expression were detected by immunochemistry in 108 bladder cancers, including 29 papillary neoplasms of low malignant potential, and 48 low and 31 high grade lesions, of which 47 were stage Ta-T1 and 61 were stage T2-T3. XPC mRNA and methylation were evaluated in fresh tissue by real-time reverse transcriptase and methylation specific polymerase chain reaction. The clinical value of altered XPC and p53 expression was analyzed in 66 bladder cancers, including 6 papillary neoplasms of low malignant potential, and 41 low and 19 high stage lesions, of which 26 were stage Ta-T1 and 40 were stage T2-T3, by the Kaplan-Meier method and Cox proportional hazards regression. RESULTS The XPC defect was associated with bladder cancer higher pathological grade, metastasis and p53 mutation. Patients with XPC(-)/p53(+) had shorter survival than those with bladder cancer without XPC(-)/p53(+) (p = 0.0127). Cox regression analysis showed that XPC expression may be a potential predictive factor for bladder cancer (p = 0.043). In bladder cancer xpc gene hypermethylation was significantly higher than in normal mucosa (p = 0.0437). CONCLUSIONS Lower mRNA may be the result of XPC hypermethylation in bladder cancer. Epigenetic defects in the XPC gene impact bladder cancer malignant behavior and may also predict poor outcome in some bladder cancer cases, as characterized by p53 pathway alteration.

Decreased nanobacteria levels and symptoms of nanobacteria-associated interstitial cystitis/painful bladder syndrome after tetracycline treatment

Introduction and hypothesisThis study was designed to detect whether nanobacteria (NB) reside in urine and bladder tissue samples of patients with interstitial cystitis/painful bladder syndrome (IC/PBS) and whether antibiotic therapy targeting these organisms is effective in reducing NB levels and IC/PBS symptoms.MethodsTwenty-seven IC/PBS patients underwent cystoscopy. Bladder biopsies and urine samples were obtained and cultured for NB, which were identified by indirect immunofluorescent staining and transmission electron microscopy.ResultsEleven bladder samples showed growth of microbes that were identified to be similar to NB. Homologous study of the 16S ribosomal RNA gene suggested that the NB could be the pathogen. For enrolled 11 patients, NB levels decreased dramatically after tetracycline treatment, and they reported significant reduction in the severity of IC/PBS symptoms.ConclusionsA high prevalence of NB was observed in female IC/PBS, and anti-NB treatment effectively improved the symptoms, which suggest that NB may cause some cases of IC/PBS.

Better Compliance Contributes to Better Nocturnal Continence With Orthotopic Ileal Neobladder Than Ileocolonic Neobladder After Radical Cystectomy for Bladder Cancer

OBJECTIVES To investigate, in a randomized controlled study, the degree of continence after the creation of orthotopic ileocolonic and ileal neobladders after cystectomy and to explore a possible mechanism for the difference in continence between these 2 types of orthotopic neobladder. METHODS From 2003 to 2007, 71 male patients underwent orthotopic lower urinary tract reconstruction with either an ileocolonic or ileal neobladder after radical cystectomy. The degrees of continence and voiding patterns were individually evaluated using urodynamic examinations and a detailed patient questionnaire. The abnormal upper tract was evaluated using intravenous urography and ultrasonography. RESULTS Complete daytime continence was achieved in 90.9% and 89.4% of the patients and functional nocturnal continence 48.5% and 76.3% of patients in the ileocolonic neobladder and ileal neobladder groups, respectively. The urodynamic data showed that the initial volume of both the ileocolonic and the ileal neobladder appeared to not be significantly different statistically, although the compliance of the ileocolonic neobladder was lower than that of the ileal neobladder (P < .05). No difference was found in the parameters such as flow rate, urethral profile length, maximal urethral pressure, or neobladder neck pressure between the 2 neobladder types. CONCLUSIONS Although the ileocolonic and ileal neobladders can both achieve a large initial volume, the ileal neobladder has an advantage in the aspect of obtaining satisfactory nocturnal continence because of its greater compliance compared with that of the ileocolonic neobladder.

LXR agonist regulates the carcinogenesis of PCa via the SOCS3 pathway.

Background: Down-regulation of suppressor of cytokine signaling 3 (SOCS3) inhibits prostate cancer (PCa) cell growth. Liver X receptors (LXRs) agonists have been recently introduced for PCa treatment. We postulated that LXR may inhibit the carcinogenesis of PCa via the SOCS3 pathway. Methods: LNCaP cells were cultured and transfected with SOCS3 small-interfering RNA (SOCS3-siRNA) and control small-interfering RNA (control-siRNA). Then cells were treated with LXR activator (GW3965). The expressions of PCa related transcript factors, e.g. transcription 3 (STAT3), nuclear factor kappa B (NF-κB) and activation protein 1(AP1) were detected by western blot assay. In vitro cell proliferation, cell migration, cell invasion and apoptosis were analysed. Nude mice were used for in vivo tumorgenesis. Results: In cells treated with control-siRNA, GW3965 enhanced SOCS3 expression and significantly inhibited the phosphorylation of STAT3, NF-κB and AP1 expressions, accompanied by dramatically reduced cellular proliferation rate, immigration and invasion of cultured cells. In cells treated with SOCS3-siRNA, the inhibitory effects of LXR activator on the phosphorylation of STAT3 and expressions of NF-κB and AP1 were totally abolished. The cell proliferation rate, immigration and invasion were markedly elevated by SOCS3 gene mutation, even with GW3965 treatment. The in vivo tumorgenesis assay showed that GW3965 significantly reduced the tumor volumes in tumor-bearing nude mice receiving saline injection, but failed to limit the tumor volume in tumor-bearing nude mice receiving SOCS3 antibody injection. Conclusion: Our results provide evidence in support of the notion that LXR agonist may regulate the carcinogenesis of PCa via the SOCS3 pathway.

Overexpressed DNA Polymerase Iota Regulated by JNK/ c-Jun Contributes to Hypermutagenesis in Bladder Cancer

Human DNA polymerase iota (pol ι) possesses high error-prone DNA replication features and performs translesion DNA synthesis. It may be specialized and strictly regulated in normal mammalian cells. Dysregulation of pol ι may contribute to the acquisition of a mutator phenotype. However, there are few reports describing the transcription regulatory mechanism of pol ι, and there is controversy regarding its role in carcinogenesis. In this study, we performed the deletion and point-mutation experiment, EMSA, ChIP, RNA interference and western blot assay to prove that c-Jun activated by c-Jun N-terminal kinase (JNK) regulates the transcription of pol ι in normal and cancer cells. Xeroderma pigmentosum group C protein (XPC) and ataxia-telangiectasia mutated related protein (ATR) promote early JNK activation in response to DNA damage and consequently enhance the expression of pol ι, indicating that the novel role of JNK signal pathway is involved in DNA damage response. Furthermore, associated with elevated c-Jun activity, the overexpression of pol ι is positively correlated with the clinical tumor grade in 97 bladder cancer samples and may contribute to the hypermutagenesis. The overexpressed pol ι-involved mutagenesis is dependent on JNK/c-Jun pathway in bladder cancer cells identifying by the special mutation spectra. Our results support the conclusion that dysregulation of pol ι by JNK/c-Jun is involved in carcinogenesis and offer a novel understanding of the role of pol ι or c-Jun in mutagenesis.